Pressurising Cast Resin

I have looked at several YOU Tube videos of turned resin/wood turned items, mostly of USA origin, nearly all of which place newly poured in a pressure pot for 24-48 hours.
Is it NECESSARY to pressurise?
Addition equ9ipment would cost £250 or more most likely.

Nevertheless am trying a largish bowl and small item simply cast and air cured. Incidentally found the resin needed many days to harden, resorting to airing cupboard after about a week.

Would REALLY appreciate any tip about resin/wood castings.

Depends on the resin. Some people just pop the bubbles at the top with a heat gun/blow torch.

I was doing a project that needed crystal clear resin 100 times so it paid for the pressure pot so use it every time.

Using pressure is necessary if you want crystal clear bubble free castings and allows you to cast deeper than without pressure. If you are going to be doing a lot of large items such as bowls you really don’t want to risk getting large trapped bubbles which will ruin your blank and end up wasting large amounts of expensive material. I cast with epoxy and have successfully made a few small blanks with barely any bubbles. I have also had a few blanks where I’ve had really large trapped bubbles rendering the blank unusable. If you are casting with embedded objects you will most certainly get bubbles if you aren’t using pressure. I would recommend investing in a pot if you plan doing this regularly as resin is just too expensive to risk wasting it. If you end up deciding it’s not for you I’m sure you would have no problem selling the pressure pot on.

Thank you for the reply Burt, I had hoped to avoid buying a pressure pot AND also a compressor, as so wisely put it’s a matter of deciding do I want to really “get into it”.

Good point about possibly selling on though.

Thank You again

Yep Burt 25 gave great advice and covered alll the bases. Bubbles are the problem and I have cast resin only to be disapointed buy the amount of bubbles trapped. However, depending on what you are combining the resin with, you canfind a low viscosity resin that takes longer to set which allows bubbles to rise to the surface and pop. Its alway a good idea to “paint” the wood parts touched by the resin to seal in any bubbles /moisture, But if your using a nice piece of timber and want a crystal clear resin… Pressure is the way to go…Good Luck

I took the plunge about 1 1/2 years ago and bought the pressure pot and compressor - haven’t looked back as working with resin is so addictive and the possibilities are limitless. The pressure pot will let you use whatever type of resin you choose. Heat is also very important and I would recommend making yourself a heat box (really cheap) let me know if you need more info.

I read this string and wondered mightily. Gasses dissolved under pressure coming out of solution when the pressure drops is what causes the bends in divers.

So why don’t at least some ‘pressurised’ blanks shatter when depressurised e.g during turning? It’s not as if pressurising totally stops gas production, surely it just minimises bubble growth?

Quite true… the way i understand it is that the bubbles remain but are reduced by the pressure to microscopic size invisable to the naked eye. I am in the process of my first bowl and resin project so just deciding if i will use a resin capsulating or coating method. Its a obe shot deal so if it goes wrong its goodbye to the bowl…

Good luck!
Having started this thread I have yet to have success, BUT learning from the responses and various YouTube posts. One thing above all other becomes plain, there is a LOT of variables, i.e. resins, hardeners, accelerators etc etc, not to mention methods.
I will definitely invest in pressure pot before further exploration!

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Its a learning curve i guess…fingers crossed lol

Happy turning

Practice on something else first…

I figured heat must be a factor so stopped attempts in my unheated garage/workshop in the cold of winter. But how warm should resin & hardener be to mix at what is a reasonable temperature to cast and cure?

Any advice please.

My resin bowl edge turned out really well, shame I cannot upload a pic… Anyway I was making a resin and wood table lamp, about 15cm tall using a plastic mold sealed with hot glue. Luckily I had stood it in a large bowlas it was on the bench and couldnt be bothered to move it out of the way. The heat from the resin melted the glue joints and it all ended up in the bottom of the bowl,so beware of large amounts of resin, they do generate a large amount of heat. As for the temp in a cold shed ( mines 6x4 and freezing) I put both resin and hardener bottles in an old tupperwer box upright and direct the warm air from an old cheap fan heater into the box When cold they will be very thick and sluggish in the bottles, a few mins in the warm air of the heater they go quite thin ready for use. The thin fluids mix better and release bubbles well. Once poured I take the item indoors to set overnight. It will be better come the warm weather but I have had no problems over winter so far…

Would love to see the finished result! Is the forum not letting you upload a picture?

Would a vacuum be better than pressure?

Putting the bottles in a bucket or bowl of warm water could be as effective.